Zno Nanowire Photoluminescence (pl) Behavioral Research

Zinc oxide (ZnO) is an important wide band gap (Eg=3.37eV) semiconductor materials, its exciton binding energy is 60meV. These characters make it is expected to be applied in the ultraviolet optoelectronic devices which can be operated at room temperature. Compared with other nanostructures, the preparation of ZnO nanowires is more simple and controllable, which is more favorable in future device application. Up to now,ZnO nanowires have been the focus research fields of ZnO low dimension structures. There are many groups investigating the preparation and photoluminescence (PL) performance of ZnO nanowires, the corresponding understandings of growth and PL mechanism of ZnO nanowires are not unified. The ultraviolet laser emission is the expected goal of ZnO nanowires, but we need deep ultraviolet excite source to pump in previous experiments, which put a disadvantageous limit in future application. In order to study these questions, we researched three topics in this paper mainly:1. We prepared ZnO nanowires using chemical vapor deposition (CVD) method based Vapor-Liquid-Solid (VLS) mechanism. Our object was getting arrayed and controllable growth of ZnO nanowires through integrating the controllable ability of VLS mechanism and merits of CVD and controlling the technique conditions of preparation. The experiment results showed we had got well nanowires on Si and sapphire substrate and the Au and Ag act catalyst respectively, we got ZnO nanowires array on Si and sapphire substrate using the Ag as catalyst.2. We measured the PL spectrum of ZnO nanowires samples excited by an ultraviolet Fluorescence Spectrophotometer in different wavelength. The spectrum and corresponding emission mechanism was analyzed. The results showed a free exciton emission and an emission based on an exciton-exciton collision process, there were few such reports in the PL spectrum excited by xenon lamp. The effective excite wavelength range is 350-355nm for the exciton-exciton collision peak and we observed a blue emission peak at about 472nm caused by zinc vacancy.3. We got the PL spectrum of ZnO nanowires using an 806nm fs laser act excited source based nonlinear optical process. The results showed the Second Harmonic Generation (SHG) phenomenon besides the exciton-exciton collision peak at 388nm, at...